A multi-lamp fluorescent light fixture involves a number of tubular fluorescent bulbs. Each fluorescent bulb is also referred to here as a fluorescent lamp. Each tube is a glass tube that contains an ionizable gas and a small portion of mercury. There are filaments at each end of the tube. By application of proper electrical voltages, the filaments can be made to heat up and to ionize the ionizable gas in the tube. After sufficient heating, if a voltage of adequate magnitude is subsequently provided between the filaments, an electrical arc can be initiated through the ionized gas in the tube between the filaments. The arc involves a flow of current from one filament, through the ionized gas, to the other filament. Energetic electrons in this current flow collide with the mercury atoms, thereby exciting the mercury atoms and causing them to emit ultraviolet radiation. The emitted ultraviolet radiation is absorbed by and excites a phosphor coating on the inside of the walls of the tube. The phosphor coating fluoresces and emits radiation in the visible spectrum (i.e., visible light). The visible light passes outward through the glass and is usable for illuminating purposes.
Some such multi-lamp fluorescent light fixtures involve a plurality of starter circuits, each commonly referred to as a “starter.” In a first step, a switch in the starter closes and forms an electrical connection between the filament at one end of a tube and the filament at the other end of the tube such that an AC current can flow from an AC power source, through an ballast, through one filament, through the closed switch of the starter, and through the second filament, and back to the AC power source. This AC current flow causes the filaments to heat. The heating of the filaments causes gas surrounding the filaments to ionize. Once the gas is ionized in this way, then the switch in the starter is opened. The opening of the switch cuts current flow through the ballast, thereby causing a large voltage spike to develop across the ballast. Due to the circuit topology, this large voltage is present between the two filaments. The voltage is large enough to strike an arc through the gas. Once the arc is established, the resistance between the two filaments through the gas decreases. This allows the current to continue to flow through the gas without a large voltage being present between the filaments. The switch is left open, the current continues to flow, filaments continue to be heated, the arc is maintained, and the current flow is regulated by the ballast. The fluorescent lamp is then on and emits visible light to illuminate an area.
In multi-lamp fluorescent light fixtures, the starters may fail. Each starter is therefore sometimes made to be a replaceable unit. Great numbers of fluorescent light fixtures with replaceable starter units are installed throughout the world. Large numbers of such fluorescent light fixtures are installed in public buildings, office buildings, and other large buildings. Quite often the fluorescent lights are left on and consume electrical energy even though the area served does not need to be illuminated. A way of preventing this waste of electrical energy is desired.
Infrared motion detecting wall switches are often employed to prevent the waste of energy due to lights being left on when lighting is not needed. If an infrared motion detector in the wall switch does not detect motion of an infrared emitter (for example, a human body) in the vicinity of the wall switch, then circuitry in the wall switch determines that the room is not occupied by a person. Presumably if a person were in the room, the person would be moving to some extent and would be detected as a moving infrared emitter. If the wall switch determines that the room is unoccupied because it does not detect any such moving infrared emitter, then the wall switch turns off the fluorescent lights on the circuit controlled by the wall switch. The wall switch turns off the fluorescent lights by cutting AC power flowing to the fluorescent lamp light fixtures through power lines hardwired into the building. If, however, the wall switch detects a moving infrared emitter, then the wall switch turns on the lights by energizing the hardwired power lines so that AC power is supplied to the fluorescent light fixtures through the hardwired power lines.
The wall switch motion detection system involving hardwired power lines embedded in the walls and ceilings of buildings is quite popular, but a wireless system has been proposed whereby each of the replaceable starter units is to be provided with an RF receiver. Each starter unit is able to selectively turn off a fluorescent lamp within a multi-lamp fluorescent light fixture to dim the light output of the fixture in response to RF commands received from a master control unit.